A patient with an aggressive form of squamous cell carcinoma (SCC) experienced complete resolution of tumors following administration of human papillomavirus (HPV) vaccine, a recent case report shows.

The patient, an immunocompetent woman, aged in her 90s, with multiple inoperable cutaneous basaloid SCCs, was treated with a combination of systemic and intratumoral delivery of 9-valent HPV vaccine, authors of the case report wrote in JAMA Dermatology.

All tumors resolved within 11 months of the first intratumoral injection, according to Anna J. Nichols, MD, PhD, department of dermatology and cutaneous surgery, University of Miami, and her coauthors.

‘These findings suggest that the 9-valent HPV vaccine can provide a therapeutic option for inoperable cutaneous SCCs, in addition to its approved use to prevent anogenital HPV infection,” they wrote.

Previously, Dr. Nichols and her coinvestigators reported a reduction in SCCs and basal cell carcinoma in 2 immunocompetent patients who had received quadrivalent HPV vaccine. Those results suggested development of these keratinocyte carcinomas in immunocompetent patients may be driven in part by HPV, the investigators said at the time.

The patient in the current report was treated with 9-valent HPV vaccine in a university-based outpatient clinic between March 2016 and February 2017.

She initially received two doses of intramuscular vaccine 6 weeks apart; 3 weeks later, she received intratumoral administration of the vaccine diluted with sterile saline, followed by three additional intratumoral doses over the next 8 months.

“The marked regression of numerous SCCs after initiation of the intratumoral injections eliminated the need for additional treatment,” Dr. Nichols and her coauthors said in the report.

A reduction in tumor size and number was seen 2 weeks after the second intratumoral dose of the 9-valent HPV vaccine, and within 11 months of the first intratumoral dose, there was no clinical or histologic evidence of SCC, they said.

The patient was left with small, violet-colored scars, along with a small pink papule, histopathologic analysis of which showed mild cellular atypia of basal keratinocytes with hyperkeratosis, according to published details of the case report.

The patient experienced mild pain in some of the tumors on days of intratumoral treatment, but no other side effects were seen, according to the authors.

The patient remained tumor free at the end of follow-up in May 2018, and there was no clinical evidence of SCC recurrence at the patient’s most recent follow-up visit, 24 months after the first intratumoral HPV dose, the researchers wrote.

It’s not clear what role the systemic vaccine doses played in the therapeutic benefit the patient experienced, authors said, noting that tumors not injected directly may have regressed because of either local vaccine dispersion or systemic, immune-mediated mechanisms.

“The potent therapeutic benefit may reflect a combination of immunologic, antiviral, and antitumor effects of 9-valent HPV vaccine,” they concluded.

Dr. Nichols had no disclosures. Study coauthors Tim Ioannides, MD, and Evangelos V. Badiavas, MD, PhD, have a patent pending for the application of human papillomavirus vaccine described in the study.